A variety of challenges face patients and physicians in the area of ocular disease management, including drug delivery to the eyes and treatment of dry eyes. Dry eye, including keratoconjunctivitis sicca, is a common ocular condition that can require therapy. Dry eye has been experienced by a broad demographic band, and is common in elderly individuals. A variety of current treatment modalities target physiological conditions that contribute to dry eye, including augmentation of normal tear fluid, enhancement of tear film component production, and methods to enhance the residence time of tears, such as blocking the tear flow from an eye into and through a lacrimal canaliculus.
Many current tear flow blockage techniques have drawbacks, including being irreversible in nature. For instance, some tear flow blockage techniques involve closing the canalicular canal by stitching the punctal opening shut or by using electrical or laser cauterization to seal the punctal opening. Although such procedures can provide the desired result of blocking tear flow to treat a dry eye, they are unfortunately not reversible without reconstructive surgery.
In addition to dry eye symptom relief, a variety of challenges face patients and physicians in the area of ocular disease or disorder management, including adequate drug or other therapeutic agent delivery to the eyes. In ocular management, for example, many current ocular drug delivery systems require repetitive manual administration and are often ineffective due to a lack of patient compliance or inadequate drug concentrations reaching the eye.
In order to treat eye infection, inflammation of an eye, glaucoma and other ocular diseases or disorders, drugs or other therapeutic agents are often required to be administered to the eye. A conventional method of drug delivery is by topical drop application to the eye's surface. Topical eye drops, though effective, can be inefficient. As one example, when an eye drop is instilled in an eye, it often overfills the conjunctival sac (i.e., the pocket between the eye and the lids) causing a substantial portion of the drop to be lost due to overflow of the lid margin and spillage onto the cheek. In addition, a large portion of the drop remaining on the ocular surface can be washed away into and through a lacrimal canaliculus, thereby diluting the concentration of the drug before it can absorbingly treat the eye. Moreover, topically applied drugs often have a peak ocular effect for about two hours post-application, after which additional applications of the drugs should be, but are often not, administered to maintain the desired drug therapeutic benefit.
To compound ocular management difficulty, patients often do not use their eye drops as prescribed. This poor compliance can be due to, for example, an initial stinging or burning sensation caused by the eye drop and experience by a patient. Instilling eye drops in one's own eye can be difficult, in part because of the normal reflex to protect the eye. Therefore, one or more drops may miss the eye. Older patients may have additional problems instilling drops due to arthritis, unsteadiness, and decreased vision. Pediatric and psychiatric populations pose difficulties as well.